Self-Moving Device Map Building for GNSS Shadow Regions

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Solution Overview

Problem

Existing automatic lawn mowers face challenges with low positioning accuracy due to shadow regions formed by trees, buildings, and obstacles, which weaken satellite navigation signals.

Innovation Solution

A map establishing method that involves exploring the actual range of shadow regions, updating the map, and controlling the self-moving device's stay time in these regions to improve working efficiency and positioning accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the self-moving device operates in shadow regions formed by trees, buildings, and obstacles, then it can cover the entire working area, but the positioning accuracy deteriorates due to weak satellite navigation signals

Engineering Contradiction:
Improveworking area coverageVSAvoidpositioning accuracy
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent segments the working area into shadow regions and non-shadow regions based on signal quality detection. By dividing the continuous working area into distinct zones with different signal characteristics, the system can apply different processing strategies to each segment, allowing complete area coverage while maintaining positioning accuracy through alternative methods in shadow regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of signal quality assessment by detecting signal strength and using this parameter to identify shadow regions. This parameter change enables the system to distinguish between areas with reliable satellite signals and those with weak signals, allowing adaptive operation that maintains positioning accuracy despite varying signal conditions across the working area.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the self-moving device spends more time exploring and mapping shadow regions, then the positioning accuracy improves, but the working efficiency deteriorates due to increased stay time in low-signal areas

Engineering Contradiction:
Improvepositioning accuracyVSAvoidworking efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by detecting and mapping shadow regions during the initial map-building phase before actual work operations. By identifying and characterizing shadow regions in advance, the system establishes accurate position information for these areas upfront, allowing subsequent work operations to proceed efficiently without repeated exploration or positioning corrections.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system performs self-service by autonomously detecting, exploring, and mapping shadow regions without external intervention. The self-moving device independently identifies areas with weak signals, spends the necessary time to establish accurate position information, and then uses this information for efficient work operations, balancing exploration time with working efficiency autonomously.

Inventive Principle:
Principle #25Self-service

3Device complexity

If the self-moving device uses satellite navigation signals for positioning, then the system complexity remains low, but the reliability deteriorates in shadow regions where signals are blocked

Engineering Contradiction:
Improvesystem complexityVSAvoidpositioning reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces an intermediary mechanism by using signal quality detection as a mediator between the satellite navigation system and the positioning function. This intermediary detects signal strength and identifies shadow regions, allowing the system to recognize when satellite signals are unreliable without adding complex alternative positioning hardware, thus maintaining low system complexity while improving positioning reliability through intelligent signal assessment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4043984B1Map building method, self-moving device, and automatic working system
Publication Date: 2025.04.09 POSITEC POWER TOOLS (SUZHOU) CO LTD
  • EP4043984B1 patent drawingFigure 1
  • EP4043984B1 patent drawingFigure 2
  • EP4043984B1 patent drawingFigure 3

AI summary

A map establishing method includes: generating a working region map and an initial shadow section, the working region map being a map of a boundary, and the initial shadow section being a part of the boundary on which a positioning signal does not meet a quality requirement; generating an initial shadow region according to the initial shadow section; exploring the initial shadow region, and collecting positioning signal quality data and positioning coordinates during exploration; and generating a corrected shadow region according to the positioning signal quality data and the positioning coordinates. A self-moving device includes: a control module; a map generation module; and an exploration module and a shadow region correction module. An automatic working system is provided with the self-moving device. An actual range of a shadow region is first explored, and then a corrected shadow region is obtained, so that a working region map can be updated, the working efficiency of the self-moving device can be improved, a staying time of the self-moving device in the shadow region can be effectively controlled, a processing mode of the shadow region can be reasonably planned, and the positioning accuracy can be improved.